CVE-2026-79670 Ech0 before 4.4.3 Stored XSS via SVG Upload
Admins can upload malicious SVG files causing stored XSS, allowing session hijacking and data exfiltration for any user.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-79670?
CVE-2026-79670 is a medium-severity cross-site scripting vulnerability in lin-snow Ech0, published on 25 Aug 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Official description
Ech0 before 4.4.3 contains a stored cross-site scripting vulnerability in the file upload endpoint that validates Content-Type using only client-supplied headers without server-side inspection. Attackers with admin privileges can upload SVG or HTML files containing JavaScript that executes in the application origin when accessed by any user, enabling session hijacking and data exfiltration.
Weakness: CWE-434
Which versions are affected by CVE-2026-79670?
3 open source packages ship an affected version, including github.com/lin-snow/ech0.
| Package | Affected | Fixed in |
|---|---|---|
github.com/lin-snow/ech0 Go | All versions | None |
github.com/lin-snow/ech0 Go | All versions | 4.4.3 |
github.com/lin-snow/ech0 Go | All versions | 4.4.3 |
How do I fix CVE-2026-79670?
Upgrade github.com/lin-snow/ech0 to 4.4.3 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-79670 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-79670 exists.
Sources
Also known as GHSA-69hx-63pv-f8f4, GHSA-mj42-9vh2-f8v3, GO-2026-5172.